The following includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art, or relevant, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
Acute coronary syndromes (ACS) encompass a wide spectrum of cardiac ischemic events ranging from unstable angina through to acute myocardial infarction (AMI). AMI presents as the most serious of these events and therefore requires rapid and accurate diagnosis. Patients who present with two or more of the described features (a history of ischemic chest discomfort, evolutionary changes on serial electrocardiogram (ECG) traces and a rise and fall in plasma cardiac biomarkers) are clearly identified as undergoing AMI.1 However, a significant proportion of patients (40%-50%) who present with suspected AMI do not have serial changes on ECG, or typical symptoms thus placing heavy emphasis on biomarker analysis for accurate diagnosis.1,2 Accurate early diagnosis of myocardial infarction facilitates prompt introduction of reperfusion treatment, including effective percutaneous or thrombolytic revascularisation and adjunctive anticoagulant and anti-platelet therapy. Such treatments are progressively less effective at reducing mortality and morbidity with each hour of delay in diagnosis and management.3-6 Given the need for accelerated decision-making in this clinical situation, there is considerable interest in the identification of biomarkers, particularly circulating biomarkers, that provide an early and specific diagnosis of acute cardiac syndromes and disorders, particularly AMI.1 Proposed biomarkers include creatine kinase-MB (CK-MB), troponin T (TnT), troponin I (TnI) BNP, N-BNP (also known as NP-BNP), BNP signal peptide (BNP-SP) and myoglobin. Time to detectable or abnormal elevation of plasma cardiac biomarkers, however, can be from up to 6 hours (myoglobin, CK-MB) to 12 hours or more (TnT, TnI, BNP, N-BNP) with peak levels often not occurring until 24-48 hours after onset of injury, imposing a window of delay upon precise diagnosis and treatment.3-6 Furthermore, both myoglobin and CK-MB are non-specific and can be secreted from extra-cardiac sources, especially during trauma or surgery.1 A need exists for a marker or suite of markers that provide early and specific information about acute cardiac syndromes and disorders such as acute cardiac injury, particularly within the first few hours of clinical presentation.
There is also a need for means to monitor vascular vulnerable plaques, which provide the substrate for acute cardiac events. Atherosclerosis is a major health problem with an annual mortality of 500,000 deaths in the United States alone. It is currently accepted that acute coronary syndromes are most commonly the result of disruption of atheromatous vulnerable plaques that are angiographically modest in severity. “Vulnerable plaque” is used to refer to a subgroup of modestly stenotic but unstable plaques that are prone to rupture and, as a result, cause sudden cardiac arrest. While coronary angiography is widely used to illustrate and monitor luminal narrowing of the coronary artery, it is unable to provide selective identification of vulnerable plaques. Most of the alternative approaches to identify vulnerable plaques are based on invasive endovascular approaches. Therefore, the development of noninvasive technology which enables vulnerable plaques to be distinguished from stable ones is critical and urgently needed to reduce the morbidity and mortality of atherosclerotic patients. It would be highly desirable if methods and devices were available to detect the unstable atherosclerotic plaque, independent of the degree of luminal diameter narrowing, and treat it before unstable angina and/or acute myocardial infarction and their consequences occur.7 
According to the National Institutes of Health (Program Announcement PA-09-196, “Ancillary Studies of Acute Kidney Injury, Chronic Kidney Disease, and End Stage Renal Disease Accessing Information from Clinical Trials, Epidemiological Studies, and Databases”), the public health and economic burden of chronic kidney disease in the United States is substantial. Diabetes and hypertension are the main causes of chronic kidney disease. The number of new cases of end-stage kidney disease in 2006 exceeded 110,000 and the number of patients undergoing treatment was over 500,000. As the United States population continues to age it is anticipated that the number of new cases of end-stage kidney disease will also increase. It has been estimated that approximately 26,000,000 people have chronic kidney disease in the US. Acute renal failure in hospitalized patients is also a significant problem in the United States, ranging from 1-15% of hospitalized patients. Medical management of acute renal failure has traditionally consisted primarily of supportive care, with renal replacement therapy for the most severe cases. Despite such interventions in acute renal failure, however, mortality rates in affected patients remain very high (>50% in some series).
Similarly, chronic renal failure (CRF) has high mortality and morbidity, for which there is no specific therapy except supportive care.8 Histologically, ischemic CRF is characterized by acute tubular necrosis; however a major limitation in approaching the disease is the lack of clinically feasible diagnostics for early detection. Early identification of chronic renal disease and timely detection of progression are challenges facing the global nephrology community, especially since a number of promising primary and secondary interventions to decelerate progression are available. In order to control costs, physicians will need to decrease progression rates of chronic renal disease to end-stage renal disease (ESRD). Current markers of kidney disease and kidney disease progression are the serum creatinine and urinary protein concentration, including microalbuminuria.8 The slope of the decrease in glomerular filtration rate (GFR) has been demonstrated to predict the timing of ESRD, and the level of proteinuria has been shown in multiple studies to correlate with kidney disease progression rates. However, their ability to recognize early kidney disease is limited. Serum creatinine concentration is dependent on the subject's age, gender, race, muscle mass, weight, degree of physical exertion, and various medications and correct interpretation of kidney function based on serum creatinine requires complex formulas. Although urinary protein is sensitive for progressive renal disease, its appearance occurs after significant renal damage has already occurred. For maximum usefulness, a biomarker of early and/or progressive kidney damage should become positive at the earliest possible point, preferably at that point that kidney damage begins to occur. There remains a strong need for discovery and validation of relevant markers, in particular for early detection.8 
A continuing problem for the World Anti-Doping Agency is the misuse of peptide/protein hormones such as erythropoietin (EPO) as performance enhancing agents by athletes. Currently, blood and urine samples are analyzed by electrophoretic or immunoassay methodologies for the presence of prohibited substances. Aside from any inherent technical issues, these determinations must account for accepted physiological levels of endogenous peptide hormones as well as determining the presence of their synthetic or recombinant forms. However it is also recognized that for some hormones in this group, newer generations of their synthetic or recombinant form have also rendered their detection more difficult when they are misused in sport, and that this issue is further complicated by (1) technological developments in the construction of synthetic or recombinant EPO, (2) controlled administration at time-points to avoid detection, (3) resultant difficulties in confirming substance levels that exceed the accepted norm, and (4) indeterminate recordings that reflect protein variability in non-specific binding of secondary antibodies (particularly in urine concentrates) and the non-specific enzymatic-induced band shifts in iso-electric tests.
Embodiments of the present invention relate to the discovery of new early markers for diagnostics, including for use in the evaluation, diagnosis and prognosis of, for example, acute coronary syndromes, acute and chronic kidney disorders and injuries, and vulnerable plaque, as well as for use in the detection of EPO doping, for example, by athletes.